Structural optimization method of hot press forming machine under thermal coupling simulation drive

Abstract

The invention discloses a structure optimization method of a hot-press forming machine under thermal-mechanical coupling simulation drive, which comprises the following steps: constructing a three-dimensional thermal-mechanical coupling finite element model, and carrying out model simplification and grid division; defining thermal-mechanical parameters of the material in the model; loading a temperature boundary condition and a mold closing pressure boundary condition, and applying an assembly constraint; solving steady-state thermal analysis by adopting a sequential coupling strategy to obtain a temperature field, and inputting the temperature field as a load into static structural analysis to obtain a thermal deformation and mechanical stress superposition result; parameterization simulation is carried out according to different thicknesses of the fixed abutment, equivalent stress of the die cavities, stress difference and deformation of the two sides of each die cavity are compared, an optimized thickness set of the fixed abutment is determined based on a preset optimized threshold value, and the final optimized thickness is obtained according to the optimized thickness set; and manufacturing the fixed abutment according to the final optimized thickness to carry out trial production verification, and if the verification index does not reach the standard, returning to adjust the thickness parameter and repeating simulation and verification until the standard is reached.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of hot press forming, in particular to a structure optimization method of a hot press forming machine under the driving of thermal coupling simulation. BACKGROUND

[0002] In the field of hot press forming technology, the existing technology mainly focuses on the basic function implementation and simple structure optimization of the equipment. Among them, the fixed base is the core basic component of the hot press forming machine, and its technical features are mainly focused on mechanical connection and basic support function. However, the existing technology has not deeply explored the internal relationship between the structure parameters of the fixed base and the overall performance of the equipment, especially the mold deformation problem caused by thermal-mechanical coupling during hot pressing, and the product qualification rate fluctuation problem caused thereby.

[0003] According to the technical feature analysis of the published patent literature, the following improvement directions exist in the existing technology: In the field of vacuum hot pressing equipment, CN207724693U patent discloses a vacuum hot press forming machine, but only mentions the basic mechanical connection between the oil press and the mold, and does not mention the fixed base structure. Although the patent CN208841656U mentions that the electric heating plate is connected to the mold through the connecting seat (fixed base), it does not improve the design of the fixed base itself; patents CN2930376Y, CN220681403U and CN219883107U etc. respectively improve from the aspects of middle plate moving guide rail, mold fixing method and demolding mechanism, but none of them touches the structure optimization problem of the fixed base. These patent literatures collectively reflect that the existing technology still stays at the basic function level in the research of the mold cooperation on the forming machine, and lacks systematic research on the relationship between the structure parameters and the equipment performance.

[0004] The defects of the existing technology mainly reflect in the following two aspects: first, the direct correlation between the thickness parameter of the fixed base and the anti-deformation ability of the equipment is not fully recognized, which leads to the structural deformation of the equipment during long-time hot pressing operation, and then affects the product precision; second, the structure layout optimization of the fixed base is not involved, which cannot effectively disperse the stress concentration generated during the hot pressing process, and limits the further improvement of the equipment performance. SUMMARY

[0005] To achieve the above object and other related objects, the present application discloses a structure optimization method of a hot press forming machine under the driving of thermal coupling simulation, comprising: Construct a three-dimensional thermal-mechanical coupling finite element model containing heating plate, fixed base, mold cavity assembly and top column, and perform model simplification and mesh division; Define the material thermal-mechanical parameters in the model; Load temperature boundary conditions and clamping pressure boundary conditions and apply assembly constraints; The sequential coupling strategy is adopted to firstly solve the steady-state thermal analysis to obtain the temperature field, and then the temperature field is input as a load into the static structure analysis to obtain the superposition result of thermal deformation and mechanical stress; The parameterized simulation is performed for different fixed base thicknesses, the mold cavity equivalent stress, the stress difference on both sides of a single mold cavity, and the deformation are compared, the optimization thickness set of the fixed base is determined based on the preset optimization threshold, and the optimization thickness set is screened to obtain the final optimization thickness. The fixed base with the final optimization thickness is manufactured for trial production verification, and if the verification index does not meet the standard, the thickness parameter is adjusted and the simulation and verification are repeated until the standard is met.

[0006] Preferably, the three-dimensional thermal-mechanical coupling finite element model comprises: The connecting edge of the mold cavity and the fixed base is rounded with a radius of 3mm to 20mm to reduce the stress singularity caused by geometric discontinuity.

[0007] Preferably, the meshing adopts tetrahedral mesh to globally discretize the model, wherein the fixed base main mesh size is 5mm to 10mm, and the mold cavity inner wall mesh is encrypted to 0.5mm to 3mm.

[0008] Preferably, the material thermal-mechanical parameters comprise: The elastic modulus is 200GPa to 220GPa, the Poisson's ratio is 0.27 to 0.30, and the thermal expansion coefficient is 10.5×10 -6 / ℃ to 12×10 -6 / ℃.

[0009] Preferably, the temperature boundary condition is 140℃ to 170℃, the clamping pressure boundary condition is 5MPa to 30MPa, and the gravitational acceleration and equipment assembly constraint conditions are applied.

[0010] Preferably, the parameterized simulation for different fixed base thicknesses comprises: A plurality of candidate thicknesses are set based on the initial thickness of the fixed base, and the candidate thickness is 1.1 times to 2.0 times of the initial thickness.

[0011] Preferably, the comparison comprises: The maximum equivalent stress value of the mold cavity is extracted for each candidate thickness, the stress difference on both sides of a single mold cavity is calculated, and the deformation of the fixed base or the mold cavity assembly is obtained.

[0012] Preferably, the preset optimization threshold comprises: The maximum equivalent stress of the mold cavity is reduced by not less than 10%, the stress difference on both sides of a single mold cavity is reduced by not less than 20%, and the deformation is not greater than 0.05mm.

[0013] Preferably, the final optimized thickness is obtained by screening the optimized thickness set. The stiffness improvement effect of each thickness value in the optimized thickness set is quantified, and the optimized thickness with better stiffness improvement effect is selected as the final optimized thickness.

[0014] Preferably, the trial production verification includes: Based on the final optimized thickness, a single batch of trial production is carried out, and the eccentricity and surface defect rates of the product are detected, wherein the eccentricity tolerance is not greater than 0.3 mm and the qualified rate threshold is not less than 90%; when the qualified rate does not reach the qualified rate threshold, the iterative optimization process of returning to the simulation stage to re-adjust the thickness parameter is executed.

[0015] By adopting the above technical scheme, the method effectively improves the anti-deformation ability and hot-pressing precision of the equipment by systematically increasing the thickness of the fixed base and optimizing the structural layout thereof. In the implementation process, firstly, a three-dimensional thermal-mechanical coupling model is constructed by using a finite element simulation platform, the connecting edge of the mold cavity and the fixed base is rounded and meshed. Subsequently, the temperature and clamping pressure boundary conditions are loaded, the thermal-mechanical superposition effect is calculated through a sequential coupling strategy, and the equivalent stress distribution of the mold cavity under different fixed base thicknesses is compared. According to the simulation results, the optimization threshold is set, the thickness of the fixed base is dynamically adjusted to the optimal range, and the closed-loop feedback is verified through actual production. The embodiments show that the method significantly improves the product qualified rate, solves the problems of inconsistent product thickness and surface defects caused by unreasonable mold structure in the traditional hot-pressing forming process, and has significant economic benefits and application value. BRIEF DESCRIPTION OF DRAWINGS

[0016] The above and other features, advantages, and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. The accompanying drawings are used to better understand the present scheme and do not constitute a limitation on the present disclosure. In the drawings, the same or similar reference numerals represent the same or similar elements, wherein: Figure 1 The method flowchart of the embodiments of the present application; Figure 2 The three-dimensional thermal-mechanical coupling finite element model constructed by the embodiments of the present application is shown in the schematic diagram.

[0017] Reference numerals: 1, heating plate; 2, fixed base; 3, mold cavity assembly; 4, top column. DETAILED DESCRIPTION

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Reference Figure 1 This invention provides a method for structural optimization of a hot press forming machine under thermo-mechanical coupling simulation, comprising: Reference Figure 2 A three-dimensional thermo-mechanical coupled finite element model including heating plate 1, fixed base 2, mold cavity assembly 3 and top column 4 was constructed, and the model was simplified and meshed. The thermodynamic parameters of the materials are defined in the model; Apply temperature boundary conditions and mold clamping pressure boundary conditions, and impose assembly constraints; A sequential coupling strategy is adopted to first solve the steady-state thermal analysis to obtain the temperature field, and then use the temperature field as a load input for static structural analysis to obtain the superposition result of thermal deformation and mechanical stress. Parametric simulations were performed for different thicknesses of the fixed base 2. The equivalent stress of the mold cavity, the stress difference between the two sides of a single mold cavity, and the deformation were compared. Based on the preset optimization threshold, the optimized thickness set of the fixed base 2 was determined, and the optimized thickness set was screened to obtain the final optimized thickness. The fixed base 2 is manufactured according to the final optimized thickness and trial production verification is carried out. If the verification indicators do not meet the standards, the thickness parameters are adjusted and the simulation and verification are repeated until the standards are met.

[0020] Preferably, the construction of the three-dimensional thermo-mechanical coupled finite element model includes: Based on the structural characteristics of hot pressing equipment, a three-dimensional thermo-mechanical coupling model is constructed using a finite element simulation platform; The edges connecting the mold cavity and the fixed base 2 are rounded with a radius of 3mm to 20mm to reduce stress singularities caused by geometric abrupt changes.

[0021] Preferably, the mesh division uses tetrahedral meshes to discretize the model globally, wherein the main mesh size of the fixed base 2 is 5mm to 10mm, and the mesh of the inner wall of the mold cavity is refined to 0.5mm to 3mm.

[0022] Preferably, the thermodynamic parameters of the material include: The material properties are defined as a high-rigidity metal with an elastic modulus of 200 GPa to 220 GPa, a Poisson's ratio of 0.27 to 0.30, and a coefficient of thermal expansion of 10.5 × 10⁻⁶. -6 / ℃~12×10 -6 / ℃.

[0023] Preferably, the temperature boundary condition is 140℃~170℃, the mold clamping pressure boundary condition is 5MPa~30MPa, and gravitational acceleration and equipment assembly constraints are applied.

[0024] Preferably, the parametric simulation for different thicknesses of the fixed base 2 includes: Multiple candidate thicknesses are set based on the initial thickness of the fixed base 2, and the candidate thicknesses are 1.1 to 2.0 times the initial thickness.

[0025] Preferably, the comparison includes: For each candidate thickness, extract the maximum equivalent stress value of the mold cavity, calculate the stress difference on both sides of a single mold cavity, and obtain the deformation of the fixed base 2 or the mold cavity assembly 3.

[0026] Preferably, the preset optimization threshold includes: The maximum equivalent stress reduction of the mold cavity shall not be less than 10%, the stress difference reduction on both sides of a single mold cavity shall not be less than 20%, and the deformation shall not be greater than 0.05 mm.

[0027] Preferably, the optimized thickness set is filtered to obtain the final optimized thickness, which includes: The stiffness improvement effect of various thickness values ​​in the quantified optimization thickness set is used to select the optimized thickness with the best stiffness improvement effect as the final optimized thickness. The quantification of the effect of thickness adjustment on structural stiffness improvement is specifically carried out through the following methods: Formula for moment of inertia of a cross section: ; Where t is the optimized thickness and b is the width of the fixed base 2; Bending stiffness formula: ; Where E is the elastic modulus and v is Poisson's ratio.

[0028] Preferably, the pilot production verification includes: Based on the final optimized thickness, a single batch of trial production is conducted, and the eccentricity and surface defect rate of the products are tested, wherein the eccentricity tolerance is no greater than 0.3 mm and the pass rate threshold is no less than 90%; when the pass rate does not reach the pass rate threshold, an iterative optimization process of returning to the simulation stage to readjust the thickness parameters is executed; preferably, the pass rate threshold in this embodiment of the invention is set to 90%, and the production verification specifically includes: The eccentricity and surface defect rate of a single batch of products are statistically analyzed. If the pass rate is less than 90%, the simulation stage is returned to readjust the thickness parameters until the requirements are met.

[0029] The effectiveness of the above method will be verified through some embodiments.

[0030] Example 1: Target of application: Large rubber glove vulcanization molds; Implementation steps: Construction of the thermo-mechanical coupling model: Based on the mold structure (top column 4 diameter 580mm, heating plate 1 size 1340mm×1340mm×46mm, fixed base 2 initial thickness 40mm), a three-dimensional model was built in ANSYS; The edge connecting the mold cavity and the fixed base 2 is rounded with an R10mm radius to eliminate geometric abrupt changes; The entire area is divided using tetrahedral meshes: the main mesh size of the fixed base 2 is 8mm, and the inner wall of the mold cavity is densified to 1.5mm; Material property definition: Elastic modulus 210 GPa, Poisson's ratio 0.28, coefficient of thermal expansion 11.5 × 10⁻⁶ -6 / ℃.

[0031] Simulation analysis and thickness optimization: The thermo-mechanical superposition effect was calculated by sequential coupling under the boundary conditions of 140℃ loading temperature and 5MPa mold clamping pressure. Comparison of simulation results for fixed base 2 with thicknesses of 40mm and 50mm: The maximum equivalent stress in the mold cavity decreased from 1312.0 MPa to 1148.1 MPa (a decrease of 12.5%). The stress difference between the two sides of a single mold cavity decreased from 300MPa to 150MPa (a reduction of 50%). According to the formula for moment of inertia of a cross section ( According to calculations, when the thickness of the fixed base 2 is increased to 50mm, the bending stiffness increases by 95.3%.

[0032] Production Validation and Iteration: The mold was manufactured with an optimized thickness of 50mm. 100 rubber gloves were produced on a trial basis, and the eccentricity was statistically analyzed (tolerance ≤ 0.3mm). The actual pass rate increased from 79.4% to 92.7%, and the closed-loop process was terminated.

[0033] Example 2: Target of application: Irregularly shaped rubber sealing component molds; Implementation steps: Construction of the thermo-mechanical coupling model: Based on the mold structure (top column 4 diameter 450mm, heating plate 1 size 1200mm×800mm×40mm, fixed base 2 initial thickness 35mm), a three-dimensional model was built in ANSYS; The edge connecting the mold cavity and the fixed base 2 is rounded with an R12mm radius. The entire area is divided into tetrahedral meshes: the main mesh size of the fixed base 2 is 6mm, and the inner wall of the mold cavity is densified to 1mm; Material property definition: Elastic modulus 215 GPa, Poisson's ratio 0.29, coefficient of thermal expansion 12 × 10⁻⁶ -6 / ℃.

[0034] Simulation analysis and thickness optimization: The thermo-mechanical superposition effect was calculated by sequential coupling under the boundary conditions of 158℃ loading temperature and 13MPa mold clamping pressure. Comparison of simulation results for fixed base 2 with a thickness of 35mm and 42mm (1.2 times the initial thickness): The maximum equivalent stress in the mold cavity decreased from 1250 MPa to 1095 MPa (a decrease of 12.4%). The stress difference between the two sides of a single mold cavity decreased from 200MPa to 150MPa (a reduction of 25%). According to the bending stiffness formula ( When the thickness of the fixed base 2 is increased to 42mm, the stiffness increases by 1.8 times.

[0035] Production Validation and Iteration: The mold was manufactured with an optimized thickness of 42mm. 100 sealing parts were produced on a trial basis, and the eccentricity was statistically analyzed (tolerance ≤ 0.3mm). The actual pass rate increased from 82% to 94%, and the closed-loop process was terminated.

[0036] Example 3: Target of application: Vulcanizing molds for automotive shock absorber pads; Implementation steps: Construction of the thermo-mechanical coupling model: Based on the mold structure (top column 4 diameter 500mm, heating plate 1 size 1000mm×800mm×50mm, fixed base 2 initial thickness 45mm), a three-dimensional model was built in ANSYS; The edge connecting the mold cavity and the fixed base 2 is rounded with an R15mm radius. The entire area is divided using tetrahedral meshes: the main mesh size of the fixed base 2 is 7mm, and the inner wall of the mold cavity is fined to 0.8mm; Material property definition: Elastic modulus 205 GPa, Poisson's ratio 0.27, coefficient of thermal expansion 11.8 × 10⁻⁶ -6 / ℃.

[0037] Simulation analysis and thickness optimization: Boundary conditions: loading temperature 152℃ and mold closing pressure 12.5MPa; Comparison of simulation results for fixed base 2 with a thickness of 45mm and 50mm (1.11 times the initial thickness): The maximum equivalent stress in the mold cavity decreased from 1280MPa to 1130MPa (a decrease of 11.7%). The stress difference between the two sides of a single mold cavity decreased from 180MPa to 130MPa (a decrease of 27.8%). According to the formula for moment of inertia of a cross section ( When the thickness of the fixed base 2 is increased to 50mm, the bending stiffness is increased by 64%.

[0038] Production Validation and Iteration: The mold was manufactured with an optimized thickness of 50mm. 100 shock-absorbing pads were produced on a trial basis, and the surface defect rate was statistically analyzed. The actual pass rate increased from 75% to 91%, and the closed-loop process was terminated.

[0039] Example 4: Target: Medical silicone glove molds; Implementation steps: Construction of the thermo-mechanical coupling model: Based on the mold structure (top column 4 diameter 350mm, heating plate 1 size 800mm×600mm×30mm, fixed base 2 initial thickness 30mm), a three-dimensional model was built in ANSYS; The edge connecting the mold cavity and the fixed base 2 is rounded with an R8mm radius. The entire area is divided using tetrahedral meshes: the main mesh size of the fixed base 2 is 5mm, and the inner wall of the mold cavity is fined to 0.5mm; Material property definition: Elastic modulus 220 GPa, Poisson's ratio 0.3, coefficient of thermal expansion 10.5 × 10⁻⁶ -6 / ℃.

[0040] Simulation analysis and thickness optimization: Boundary conditions: loading temperature 170℃ and mold clamping pressure 20MPa; Comparison of simulation results for fixed base 2 with a thickness of 30mm and 36mm (1.2 times the initial thickness): The maximum equivalent stress in the mold cavity decreased from 1350MPa to 1188MPa (a decrease of 12.0%). The stress difference between the two sides of a single mold cavity decreased from 150MPa to 100MPa (a decrease of 33.3%). According to the bending stiffness formula ( When the thickness is increased to 36mm, the stiffness increases by 2.1 times.

[0041] Production Validation and Iteration: The mold was manufactured with an optimized thickness of 36mm. 100 silicone gloves were produced on a trial basis, and the product qualification rate was calculated. The actual pass rate increased from 80% to 93%, and the closed-loop process was terminated.

[0042] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the meaning consistent with their meaning in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined.

[0043] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the embodiments of the present invention are not limited to the described order of actions, because according to the embodiments of the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions involved are not necessarily essential to the embodiments of the present invention.

[0044] As can be seen from the above description of the embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments of this application.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for structural optimization of a hot press molding machine driven by thermo-mechanical coupling simulation, characterized in that, include: A three-dimensional thermo-mechanical coupled finite element model including a heating plate, a fixed base, a mold cavity assembly, and a top column was constructed, and the model was simplified and meshed. The thermodynamic parameters of the materials are defined in the model; Apply temperature boundary conditions and mold clamping pressure boundary conditions, and impose assembly constraints; A sequential coupling strategy is adopted to first solve the steady-state thermal analysis to obtain the temperature field, and then use the temperature field as a load input for static structural analysis to obtain the superposition result of thermal deformation and mechanical stress. Parametric simulations were performed for different fixed base thicknesses to compare the equivalent stress of the mold cavity, the stress difference between the two sides of a single mold cavity, and the deformation. Based on a preset optimization threshold, the optimized thickness set of the fixed base was determined, and the optimized thickness set was screened to obtain the final optimized thickness. The fixed base is manufactured according to the final optimized thickness and trial production verification is carried out. If the verification indicators do not meet the standards, the thickness parameters are adjusted and the simulation and verification are repeated until the standards are met.

2. The method according to claim 1, characterized in that, The construction of the three-dimensional thermo-mechanical coupled finite element model includes: The edges connecting the mold cavity and the fixed base are rounded with a radius of 3mm to 20mm to reduce stress singularities caused by geometric abrupt changes.

3. The method according to claim 1, characterized in that, The meshing process uses tetrahedral meshes to discretize the model across the entire domain. The mesh size of the fixed base body is 5mm to 10mm, and the mesh of the inner wall of the mold cavity is refined to 0.5mm to 3mm.

4. The method according to claim 1, characterized in that, The thermodynamic parameters of the material include: Its elastic modulus is 200 GPa to 220 GPa, its Poisson's ratio is 0.27 to 0.30, and its coefficient of thermal expansion is 10.5 × 10⁻⁶. -6 / ℃~12×10 -6 / ℃.

5. The method according to claim 1, characterized in that, The temperature boundary condition is 140℃~170℃, the mold clamping pressure boundary condition is 5MPa~30MPa, and gravitational acceleration and equipment assembly constraints are applied.

6. The method according to claim 1, characterized in that, The parametric simulation for different fixed base thicknesses includes: Multiple candidate thicknesses are set based on the initial thickness of the fixed base, and the candidate thicknesses are 1.1 to 2.0 times the initial thickness.

7. The method according to claim 1, characterized in that, The comparison includes: For each candidate thickness, extract the maximum equivalent stress value of the mold cavity, calculate the stress difference on both sides of a single mold cavity, and obtain the deformation of the fixed base or mold cavity assembly.

8. The method according to claim 1, characterized in that, The preset optimization thresholds include: The maximum equivalent stress reduction of the mold cavity shall not be less than 10%, the stress difference reduction on both sides of a single mold cavity shall not be less than 20%, and the deformation shall not be greater than 0.05 mm.

9. The method according to claim 1, characterized in that, The optimized thickness set is filtered to obtain the final optimized thickness, which includes: The stiffness improvement effect of each thickness value in the quantified optimization thickness set is used to select the optimized thickness with the better stiffness improvement effect as the final optimized thickness.

10. The method according to claim 1, characterized in that, The pilot production verification includes: Based on the final optimized thickness, a single batch of trial production is carried out, and the eccentricity and surface defect rate of the products are tested. The eccentricity tolerance is no greater than 0.3 mm and the pass rate threshold is no less than 90%. When the pass rate does not reach the pass rate threshold, the iterative optimization process of returning to the simulation stage to readjust the thickness parameters is executed.

Images